Severe Thunderstorm Watch 339

Issued

Jul 6, 2021, 5:00 PM MDT (23:00 UTC)

Expired

Jul 6, 2021, 10:51 PM MDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

Counties Big Horn County, MT, Custer County, MT, Musselshell County, MT, Powder River County, MT, Rosebud County, MT, Treasure County, MT, Yellowstone County, MT

The Billings radar (KBLX), 141 km from the middle of the area, began a volume at 23:00 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Two or more tornadoes

5%

One or more EF2 to EF5 tornadoes

2%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 1165 Severe potential...watch possibleJul 6, 2:37 PM MDT
• Mesoscale Discussion 1170 Severe thunderstorm watch 339Jul 6, 6:40 PM MDT
• Mesoscale Discussion 1173 Severe thunderstorm watch 339Jul 6, 10:27 PM MDT

269 
WWUS20 KWNS 062256
SEL9  
SPC WW 062256
MTZ000-070500-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 339
NWS Storm Prediction Center Norman OK
500 PM MDT Tue Jul 6 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Southeast Montana

* Effective this Tuesday afternoon and evening from 500 PM until
  1100 PM MDT.

* Primary threats include...
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible

SUMMARY...Thunderstorms have developed north of Billings ahead of an
approaching upper disturbance.  These storms are likely to persist
for several hours, tracking southeastward across the watch area. 
Large hail and damaging winds will be possible.

The severe thunderstorm watch area is approximately along and 70
statute miles east and west of a line from 80 miles west northwest
of Miles City MT to 65 miles west southwest of Broadus MT. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 335...WW 336...WW
337...WW 338...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
29025.

...Hart

Severe Thunderstorm Watches in Montana, 2021Every severe thunderstorm watch in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.